Idle-Stop not working ... cold weather or fault ?

[richardfrost]

I'd suggest though that rather than turning the feature off maybe people could just learn to work with it.

If it's all the same to you, I think I'll just turn it off. One less thing to distract me.

[mikebore]

I'd suggest though that rather than turning the feature off maybe people could just learn to work with it.

If it's all the same to you, I think I'll just turn it off. One less thing to distract me.

I agree with your earlier posts, not worth worrying about. Most of the time it works fine and predictably, very occasionally it is not available for no obvious reason. Either way I don't find it a distraction, and the point mentioned earlier about light and firm pressure is intuitive.

Note I am pretty sure you can only turn it off per journey....the off setting by the gear lever is re-set each journey.

[andruec]

Various tests of various manufacturers of cars suggest it can save between 5% and 10%.

That is a very big number, which is failing my BS test

Maybe the explanation is in the definition/calculation of "5-10%"...can you give any links to help understand.

http://www.nrcan.gc.ca/energy/efficiency/transportation/cars-light-trucks/buying/16757
http://www.consumerreports.org/cro/news/2012/06/stop-idling-stop-start-systems-have-great-promise-for-saving-fuel/index.htm
https://www.edmunds.com/car-reviews/features/do-stop-start-systems-really-save-fuel.html

It is of course going to vary depending on the type of journey. For a 200 mile motorway drive idle-stop is not going to save you anything. But for a vehicle used for the school-run or commuting the savings could be quite significant. I've seen the difference. Last year Southam Road in Banbury (a primary access route) was being dug up. If I got caught by the lights - which were a long cycle - I'd be sitting there for a minute with the fuel readout fixed. When the idle-stop finally gave up and switched the engine back on I could see the mpg figure dropping by a tenth every 20 seconds. Catching those lights at the worst possible time would 'cost me' nearly .4mpg according to the display.

https://www.quora.com/How-much-gas-does-a-car-burn-per-hour-while-idling

"0.02 L/min"

So if I'm stationary for two minutes on my daily commute each way (reasonable) that's nearly 0.1 litres of fuel that could be saved. My entire commute is 12 miles each way which is about 2.5 litres in total. So I'm not far off that 5% saving. Now in truth my commute is mostly rural so 9 miles of it won't benefit from idle-stop anyway. For someone with a shorter commute or more horrible urban experience than my 2 miles of Banbury the savings would be a lot higher.

[mikebore]

Various tests of various manufacturers of cars suggest it can save between 5% and 10%.

That is a very big number, which is failing my BS test

Maybe the explanation is in the definition/calculation of "5-10%"...can you give any links to help understand.

http://www.nrcan.gc.ca/energy/efficiency/transportation/cars-light-trucks/buying/16757
http://www.consumerreports.org/cro/news/2012/06/stop-idling-stop-start-systems-have-great-promise-for-saving-fuel/index.htm
https://www.edmunds.com/car-reviews/features/do-stop-start-systems-really-save-fuel.html

It is of course going to vary depending on the type of journey. For a 200 mile motorway drive idle-stop is not going to save you anything. But for a vehicle used for the school-run or commuting the savings could be quite significant. I've seen the difference. Last year Southam Road in Banbury (a primary access route) was being dug up. If I got caught by the lights - which were a long cycle - I'd be sitting there for a minute with the fuel readout fixed. When the idle-stop finally gave up and switched the engine back on I could see the mpg figure dropping by a tenth every 20 seconds. Catching those lights at the worst possible time would 'cost me' nearly .4mpg according to the display.

https://www.quora.com/How-much-gas-does-a-car-burn-per-hour-while-idling

"0.02 L/min"

So if I'm stationary for two minutes on my daily commute each way (reasonable) that's nearly 0.1 litres of fuel that could be saved. My entire commute is 12 miles each way which is about 2.5 litres in total. So I'm not far off that 5% saving. Now in truth my commute is mostly rural so 9 miles of it won't benefit from idle-stop anyway. For someone with a shorter commute or more horrible urban experience than my 2 miles of Banbury the savings would be a lot higher.

Thanks! very interesting.

The first three links all said they had measured in city driving, rather than averaged out over a motorway/rural/city mix which makes the 5-10% more credible.

Your numbers are interesting. I thought 0.01L/min was nearer the average of the answers in that link than .02L/min, assuming they are talking US gals. This gives lower than 5% for your mixed rural/city commute but probably consistent with 5% for a city cycle.

So bottom line of my nit-picking is I'll buy 5-10% saving in city driving.

[ColinB]

Fascinating discussion, but if I may go back to the original issue.

Regarding my original Q, it looks like it's only me (thanks for the input) so I'll need to investigate further. I'll try some battery voltage checks and taking the car for a really long run to charge it fully.

So today I dug out my multimeter, which (at various times) gave voltages across the battery between 12.5 and 12.7 with the engine stopped and 14.25 with the engine running. Ambient temperature throughout was between 2 & 3 degrees. That all sounds fine to me, so the battery itself and the charging system seem OK (?)

I've also done a run totalling 80 miles: 40 each way, with a pause in the middle to check voltages and give the car a chance to start anew as per John Ratsey's suggestion: idle-stop didn't function at any time. The multi-display messages varied, sometimes it was just the circled-A-with-a-line-through-it, sometimes it had the low battery indication as well. At the end of the run I got the "low battery" indication, but yet measured the battery voltage at 12.7V.

Called my local dealer, who immediately knew what I was talking about because they've seen it before and have had to "reset the system" (whatever that means) on other cars. So I'm booked in for that ... although not until 1st March because (apparently) they are "snowed under with airbag recall work".

[guest6112]

I thought it's main purpose was to boost the fuel consumption figures during the official testing.

[mikebore]

I thought it's main purpose was to boost the fuel consumption figures during the official testing.

 

[guest6112]

I think the urban test is where the 5 to 10% comes from.

[andruec]

because (apparently) they are "snowed under with airbag recall work".

Well, that's made me feel a whole lot safer

[John Ratsey]

Called my local dealer, who immediately knew what I was talking about because they've seen it before and have had to "reset the system" (whatever that means) on other cars. So I'm booked in for that ... although not until 1st March because (apparently) they are "snowed under with airbag recall work".

Somewhere (my HR-V manual?) I read that the reset involves disconnecting / reconnecting the batttery. I did that on my HR-V (which is when I discovered that the earth cable wasn't very tight on the battery terminal)http://www.hrvforums.co.uk/viewtopic.php?f=11&t=289&start=30#p2849] [url]http://www.hrvforums.co.uk/viewtopic.php?f=11&t=289&start=30#p2849[/url]. One/both of disconnecting and then tightening the clamp properly got the auto stop working. Note that the radio loses its code and briefly complains when you turn the ignition key but it then finds that the code is stored somewhere. If you can't find something similar in the Jazz manual then I'll search the HR-V manual for the relevant info.

Also make sure that all the electrical connections are tight. A resistance of 0.01 ohms will cause a voltage drop of 1V if the starter motor pulls 100 Amps.

[guest6112]

I believe the airbag problem is a historic one affecting many car manufacturers. The UK Jazz is too young to be affected.

[VicW]

The airbag problem is a current one and cars, including the Jazz, are being booked in now for the work to be done as spare parts are now available.
There is plenty on this forum on the subject.

Vic.

[guest6112]

Are any of the Mk3s affected? I should have specified the GK model,  older ones could be affected. I have just checked mine on the Honda UK recall check website and it has no recalls.

[VicW]

I checked my Mk 2 2011 model not long ago which said that no recalls were outstanding.
A couple of weeks ago I got an email asking me to book my car in for the airbag job !

Vic.

[guest6112]

It seems that only cars built before 2015 a affected. They must be recalling them in batches.

http://www.whatcar.com/news/biggest-ever-car-recall-sparked-by-airbag-fault/